In one sense, there are two types of wrenches: one type has fixed fastener engaging jaws and one type has movable fastener engaging jaws. Prior art adjustable jaw wrenches are almost always continuously adjustable, of which the crescent wrench is the most common example. Continuously adjustable wrenches have an advantage because one does not need to know the size of the fastener to be worked on. One merely adjusts the wrench to fit the torque receiving faces of the fastener. On the other hand, wrenches having fixed jaws possess a number of advantages as shown by the popularity of open end and box end wrenches that has persisted for generations.
Disclosures of adjustable jaw devices of interest relative to this invention are found in U.S. Pat. Nos. D321,310; 1,811,148; 5,048,380; 5,183,055 and 5,222,419. There are a number of adjustable wrenches in the prior art that include a scale between the movable jaws so the user can determine the spacing between the movable jaws and thus determine the size of the fastener being worked on. Disclosures of this type are found in U.S. Pat. Nos. 2,722,150; 3,948,120; 4,326,436; 4,454,791; 4,653,357 and 5,375,490. None of these disclosures provide a wrench having a dial to specify the wrench size in both English and metric units.